Temporal changes of multiple redox couples from proliferation to growth arrest in IEC-6 intestinal epithelial cells

Abstract

Changes in intracellular redox couples and redox reactive molecules have been implicated in the regulation of a variety of cellular processes, including cell proliferation and growth arrest by contact inhibition. However, the magnitude, direction, and temporal relationship of redox changes to cellular responses are incompletely defined. The present work sought to characterize redox and metabolic changes associated with proliferative stages to contact inhibition of growth in rat IEC-6 intestinal epithelial cells. From the first day of culture until 1 day before confluence, an increase in GSH concentrations and a significant reduction in the redox potential of the GSSG/2GSH couple were observed. These changes were accompanied by a decrease in relative reactive oxygen species (ROS) and nitric oxide (NO) concentrations and oxidation of the redox potential of the NADP(+)/reduced NADP and NAD(+)/NADH couples. Postconfluent cells exhibited a significant decrease in GSH concentrations and a significant oxidation of the GSSG/2GSH couple. When cell proliferation decreased, relative ROS concentrations increased (P < 0.01), whereas NO concentrations remained unchanged, and the NAD(+)/NADH couple became more reduced. Together, these data indicate that the redox potential of distinct couples varies differentially in both magnitude and direction during successive stages of IEC-6 growth. This finding points out the difficulty of defining intracellular redox status at particular stages of cell growth by examining only one redox species. In addition, the data provide a numerical framework for future research of regulatory mechanisms governed by distinct intracellular redox couples.

Keratinocyte growth factor down-regulates intracellular ROS production induced by UVB

“…2A), confirming the relevance of KGFR activation in the control of the cell responses to UVB. The difference in ROS content observed between the preconfluent and confluent HaCaT cells is consistent with previous reports which describe a higher production of intracellular ROS in sparse compared to confluent cells [35][36][37]. Similar results were obtained also in human primary keratinocytes grown at confluence to express higher levels of the receptor: UVB exposure induced a significant increase of ROS production (mean values AE CI 95% of the fluorescence intensity measurement: 15.62 AE 0.84, Fig.…”

Induction of Apoptosis by the Medium-Chain Length Fatty Acid Lauric Acid in Colon Cancer Cells due to Induction of Oxidative Stress

“…Butyrate did not induce apoptosis in the IEC-6 cell line, nor did it decrease GSH availability, although cells accumulated in the G0/G1 phase at the initial time points. Interestingly, butyrate generated lower levels of ROS than PBS control values, which is consistent with previous studies [30]. …”

Oxidative Shielding or Oxidative Stress?

“…Cycling cells have higher NADPH/NADP ϩ ratios than postmitotic cells (Attene-Ramos et al, 2005). Cultured cells must double their biomass each day in preparation for division.…”